Example 1: Creating a default connection and two other
    connections

    The following log file from an interactive SQL connection shows
    three databases attachments: personnel_northwest, personnel_
    northeast, and personnel_southeast. (By not specifying an alias
    for personnel_northwest, the default alias is assigned.) Several
    connections are established, including EAST_COAST, which includes
    both personnel_northeast and personnel_southeast.

    Use the SHOW DATABASE statement to see the database settings.

    SQL> --
    SQL> -- Attach to the personnel_northwest and personnel_northeast databases.
    SQL> -- personnel_northwest has the default alias, so personnel_northeast
    SQL> -- requires an alias.
    SQL> -- All the attached databases comprise the default connection.
    SQL> --
    SQL> ATTACH 'FILENAME personnel_northwest';
    SQL> ATTACH 'ALIAS NORTHEAST FILENAME personnel_northeast';
    SQL> --
    SQL> -- Add the personnel_southeast database.
    SQL> --
    SQL> ATTACH 'ALIAS SOUTHEAST FILENAME personnel_southeast';
    SQL> --
    SQL> -- Connect to personnel_southeast.  CONNECT does an
    SQL> -- implicit SET CONNECT to the newly created connection.
    SQL> --
    SQL> CONNECT TO 'ALIAS SOUTHEAST FILENAME personnel_southeast'
    cont>     AS 'SOUTHEAST_CONNECTION';
    SQL> --
    SQL> -- Connect to both personnel_southeast and personnel_northeast as
    SQL> -- EAST_COAST connection. SQL replaces the current connection to
    SQL> -- the personnel_southeast database with the EAST_COAST connection
    SQL> -- when you issue the CONNECT statement. You now have two different
    SQL> -- connections that include personnel_southeast.
    SQL> --
    SQL> CONNECT TO 'ALIAS NORTHEAST FILENAME personnel_northeast,
    cont>     ALIAS SOUTHEAST FILENAME personnel_southeast'
    cont>     AS 'EAST_COAST';
    SQL> --
    SQL> -- The DEFAULT connection still includes all the attached databases.
    SQL> --
    SQL> SET CONNECT DEFAULT;
    SQL> --
    SQL> -- DISCONNECT releases the connection name EAST_COAST, but
    SQL> -- does not detach from the EAST_COAST databases because
    SQL> -- they are also part of the default connection.
    SQL> --
    SQL> DISCONNECT 'EAST_COAST';
    SQL> --
    SQL> SET CONNECT 'EAST_COAST';
    %SQL-F-NOSUCHCON, There is not an active connection by that name
    SQL> --
    SQL> -- If you disconnect from the default connection, and have no other
    SQL> -- current connections, you are no longer attached to any databases.
    SQL> --
    SQL> DISCONNECT DEFAULT;
    SQL> SHOW DATABASES;
    %SQL-F-ERRATTDEF, Could not use database file specified by SQL$DATABASE
    -RDB-E-BAD_DB_FORMAT, SQL$DATABASE does not reference a database known to Rdb
    -RMS-E-FNF, file not found

    Example 2: Disconnecting a connection and starting a new
    connection with the same database

    In this example, there are two connections: the default
    connection and a current connection, CA. Both connections use
    the personnel_ca database. Use the SHOW DATABASE statement to see
    the database settings.

    SQL> --
    SQL> -- Establish a default connection by attaching to the personnel_ca
    SQL> -- database.
    SQL> --
    SQL> ATTACH 'FILENAME personnel_ca';
    SQL> SHOW CONNECTIONS;
    ->      RDB$DEFAULT_CONNECTION
    SQL> --
    SQL> -- Start a new connection called CA.
    SQL> --
    SQL> CONNECT TO 'FILENAME personnel_ca'
    cont>     AS 'CA';
    SQL> SHOW CONNECTIONS;
            RDB$DEFAULT_CONNECTION
    ->      CA
    SQL> --
    SQL> -- The DISCONNECT CURRENT statement releases the connection name CA,
    SQL> -- although the database personnel_ca still belongs to the default
    SQL> -- connection.
    SQL> --
    SQL> DISCONNECT CURRENT;
    SQL> SHOW CONNECTIONS;
    ->      RDB$DEFAULT_CONNECTION
    SQL> --
    SQL> -- Even though the database personnel_ca is still attached, CA
    SQL> -- is no longer an active connection.
    SQL> --
    SQL> SET CONNECT 'CA';
    %SQL-F-NOSUCHCON, There is not an active connection by that name
    SQL> --
    SQL> -- The original ATTACH statement comprises the default connection.
    SQL> -- The DISCONNECT DEFAULT statement detaches the default connection.
    SQL> --
    SQL> DISCONNECT DEFAULT;
    SQL> SHOW DATABASES;
    %SQL-F-ERRATTDEF, Could not use database file specified by SQL$DATABASE
    -RDB-E-BAD_DB_FORMAT, SQL$DATABASE does not reference a database known to Rdb
    -RMS-E-FNF, file not found